/*
project-83113-unpacker.c -- some obscure mobile game assets unpacker
Copyright (C) 2024 Alibek Omarov

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
*/
#include <stdio.h>
#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>

struct archive_file_t
{
	uint32_t offset;
	uint32_t size;
	uint32_t namelen;
	struct archive_file_t *next;
	char name[];
};

static struct archive_file_t *file_list;

static void error( const char *fmt, ... )
{
	va_list va;

	va_start( va, fmt );
	vprintf( fmt, va );
	va_end( va );

	exit( 1 );
}

int read_directory( FILE *f, uint32_t directory_size )
{
	struct archive_file_t *archive_file;
	uint32_t offset;
	uint32_t size;
	uint32_t namelen;

	if( fread( &namelen, 1, sizeof( namelen ), f ) != sizeof( namelen ))
		error( "can't read file name length at %d\n", ftell( f ));

	archive_file = malloc( sizeof( *archive_file ) + namelen + 1 );
	archive_file->namelen = namelen;
	if( fread( archive_file->name, namelen, 1, f ) != 1 )
		error( "can't read file name at %d\n", ftell( f ));
	archive_file->name[namelen] = 0;

	if( fread( &size, 1, sizeof( size ), f ) != sizeof( size ))
		error( "can't read file size at %d\n", ftell( f ));

	archive_file->size = size;

	if( fread( &offset, 1, sizeof( offset ), f ) != sizeof( offset ))
		error( "can't read file offset at %d\n", ftell( f ));

	archive_file->offset = offset + directory_size + 8;
	archive_file->next = file_list;
	file_list = archive_file;

	printf( "discovered %s at 0x%x size 0x%x\n", archive_file->name, offset, size );

	return 1;
}

void create_directory( char *path )
{
	char *p = path;
	int err;

	while(( p = strchr( p, '/' )))
	{
		*p = 0;
		err = mkdir( path, 0777 );
		if( err < 0 && errno != EEXIST )
			error( "can't create directory at %s: %s\n", path, strerror( errno ));
		*p = '/';
		p++;
	}
}

void extract_files( FILE *f )
{
	struct archive_file_t *file;

	for( file = file_list; file; file = file->next )
	{
		char *tmp = malloc( file->size );
		if( fseek( f, file->offset, SEEK_SET ) < 0 )
			error( "can't seek to %d: %s\n", file->offset, strerror( errno ));

		if( fread( tmp, file->size, 1, f ) != 1 )
			error( "can't read file %s\n", file->name );

		create_directory( file->name );

		FILE *out = fopen( file->name, "wb" );
		if( !out )
			error( "can't create file %s: %s\n", file->name, strerror( errno ));

		if( fwrite( tmp, file->size, 1, out ) != 1 )
			error( "can't write file %s: %s\n", file->name, strerror( errno ));

		printf( "extracted %s...\n", file->name );
		free( tmp );
		fclose( out );
	}
}

int main( int argc, char **argv )
{
	FILE *f;

	if( argc != 2 )
		error( "usage: %s <data.pap or main.2.corp.ncsoft.belle.obb>\n", argv[0] );

	f = fopen( argv[1], "rb" );
	uint32_t file_size, directory_size;

	fseek( f, 0, SEEK_END );
	file_size = ftell( f );
	fseek( f, 0, SEEK_SET );

	printf( "file size is %d\n", file_size );
	if( fread( &directory_size, 1, sizeof( directory_size ), f ) != sizeof( directory_size ))
		error( "can't read directory size\n" );

	// skip 4 bytes of unknown stuff
	fseek( f, 4, SEEK_CUR );

	while( ftell( f ) < directory_size + 8 )
		read_directory( f, directory_size );

	extract_files( f );

	return 0;
}